Power transmission device



Sept. 29, 1936. c. B. STRANDGREN 2,055,951

- 'POWER TRANSMISSION DEVICE Original Filed Oct. 25, 1953 2 Sheets-Sheet1 C. Eg /T27 7 1 an.

Se t. 29, 1936. c. B. STRANDGREN 2,055,951

POWER TRANSMISSION DEVICE Original Filed Oct. ,25, 1935 2 Sheets-SheetISnoeritor 02B. Sfranqgre (Ittomegs Patented Sept. 29, 1936 UNITEDSTATES PATENT OFFIE Original application October 25, 1933, Serial No.695,188. Divided and this application May 10, 1935, Serial No. 20,858.In France November 1 Claim.

The present invention, which is a division of my copending applicationNo. 695,188, relates to a power transmission device of the homo-kinetictype, adapted for making connection between two parallel or practicallyparallel shafts, and more particularly between two parallel shafts whosespacing is variable during their rotation. The said device which is infact intended to replace the joint having two perpendicular slots,termed Oldham joint, may be utilized especially in order to connect avehicle wheel, mountd on springs, with its driving device (driving shaftof a motor vehicle, electric motor of an electric locomotive or thelike).

The preferred use considered by the applicant consists in the connectionbetween the shaft of a feathering paddle wheel, such as the onedescribed in his French Patent No. 700,476 of November 20th, 1929, andthe rotary device of variable eccentricity which controls theoscillation of the oscillating blades or paddles.

According to the invention the power transmission mechanism comprisestwo sets of pivotal links, the links of one set having the same length,25 being pivoted at points on the driving (or the driven) member whichare situated at the apices of a regular polygon whose center is on theaxis of rotation of said member and being connected together by couplingbars for holding the links n of said set in parallel relation with oneanother, and the links of the other set having also the same length,being pivoted at points on the driven (or the driving) member situatedat the apices of a regular polygon whose center is on the axis of saidsecond member, and being each pivoted to a corresponding link of thefirst set.

Owing to said arrangement the device is statically and dynamicallybalanced and may be advantageously used when the driving and driven 40members are adapted to rotate at high speeds.

Furthermore the system of bars for coupling and maintaining in parallelrelation the links of each set is very light and not bulky and does notrea connection between two of the link members and taken on line 5-5 ofFig. 1. 1

Fig. 6 is an enlarged sectional view on line 6-6 of Fig. 1 showing theconnection of the driving member to the driven member.

The embodiment shown in the drawings is adapted for connection of adriving member A (for instance a disc rotating on axis A0) with a drivenmember B (for instance a disc rotating on axis Bo) and comprises atleast three pairs of links, connected together and with the drivingmember A and the driven member B in the following manner:

Three links 52 of equal length are pivoted respectively at points A1,A2, A3 of member A upon axes 56. These points are situated at the apicesof an equilateral triangle whose center is A0. Three other links 54 ofequal length are respectively pivoted in the same manner at points B1,B2, B3 of member B which are situated at the spices of an equilateraltriangle whose center is Bo and which is equal to triangle A1, A2, A3.The free end of each link 54 is pivoted to a corresponding link 52, atC, D, or E, so that members A and B are connected together at threepoints through three pairs of links 52-54. Said three pairs of links arealso connected together by pivoted coupling bars 55 whose length isequal to the length of the sides of triangles A1, A2, A3, B1, B2, B3 inorder that links 52 always remain parallel with one another. Due to saidcoupling bars, links 54 will also remain parallel with one another.

Preferably, each link 52 is rigid with axis 56 which extends throughmember A and carries, on the other side of said member, a link 53. Thethree links 53 are of equal length and parallel with one another, andmake a determined angle with links 52, for instance an angle of 180 asshown in Fig. 2. The coupling bars 55 are pivoted at the free ends 0 D Eof links 53. Said arrangement has the advantage that the weight of links53 and bars 55 may be so chosen as to counterbalance the weight of links52, 54. Furthermore the coupling of.four links at the same points C D Eis avoided since bars 55 are pivoted at C D E instead of being pivotedat C D E.

In the case in which the shafts to be connected are not exactlyparallel, use may be made of a hinged joint for the links 52 or 54, theaxis of the hinge being situated in the plane of the figure andperpendicular to the axis of the corresponding link.

It will be noted that in the apparatus shown in the drawings, theeccentricity of the shaft will never be annulled and this may beadvantageous for certain applications. If, on the contrary, it isdesired that the eccentricity may be annulled, the links 52 and 54 willbe given equal lengths;

Obviously, it is possible to increase at will the number of pairs oflinks 52, 54 which connect the driving and the driven members. In allthe cases the points A1, A2, A3 of member A are so chosen on said memberthat they will be situated at the apices of a regular polygon whosecenter is An. In the same manner, the points B1, B2, B3 will always besituated at the apices of another regular polygon the center of which isBo and which is equal to the first one.

Obviously, at each of the pivot points of links 52, 53, 54 and bars 55,between the pivot axis and the corresponding links, either smoothbearings, or ball or roller bearings, and preferably needle bearings(the rollers consisting of fine needles in great number) which take up avery small space, may be used. As the relative movement of the links aremovements of oscillation having a limited amplitude, elastic joints ofthe silentbloc type may also be used, such joints dispensing with alllubrication and allowing to connect shafts which are not exactlyparallel.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is:

A power transmission mechanism for connecting a driving member with adriven member rotating about substantially parallel axes of varyingspacing, which comprises a first set of at least three parallel links ofequal length pivoted on the driving member at points situated at theapices of a regular polygon concentric with the axis of rotation of saiddriving member, a. second set of parallel links of equal length pivotedon the driven member at points situated at the apices of a regularpolygon concentric with the axis of rotation of said driven member, thefree end of each link of one set being pivoted to the free end of acorresponding link of the other set, a set of parallel arms rigidlyconnected with the respective links of one set, on the opposite side ofthe corresponding member, said arms having a common length substantiallyequal to that of said latter links, and said links and said armsextending in substantially opposite directions, and floating couplingmeans pivotally connected to the free ends of said arms.

CARL BRUNO STRANDGREN.

